Hello everyone,
I am new in the field of mass spectrometry and I have some questions about the preparation of the matrix and analyte for a MALDI TOF analysis.
I prepared a saturated solution of sinapinnic acid in absolute ethanol and I mixed 1 µL of this solution with 1 µL of BSA (20mg/mL) in water.
I put 1 µL on the plate and I let dried.
When I analysed the result, the signal is weak and I can't determine the peaks of BSA.
Does anyone can tell me what's wrong in my protocole?
Thank you in advance,
Sébastien Brûlé
Dear Sébastien,
First of all, the concentration of BSA seems to be very high. In MALDI TOF MS an excess of the matrix is mandatory. Try to measure BSA dilutions. Second, MALDI TOF MS is not really sensitive in the high m/z region (MW of BSA is 66 kD). The best sensitivity is obtained when tryptic digests are analyzed (reflector mode, m/z region 400 - 3000).
Best, -Peter
(see also the link)
www.sdstate.edu/chem/mass-spec/tutorials/upload/Maldi-Sample-Preparation.pdf
Thank you Peter for your reply.
I tried with lower concentrations of BSA but it didn't work too.
After reading your link, I think the ethanol is not well suitable. Have you tried to dissolve your matrix in ethanol?Or do you use 30ACN+0.1%TFA?
Best,
Sébastien
Dear Sébastien,
Yes, using 33% ACN, 0.1 TFA solution for matrix prep would be a good starting point. There are, however, a number of different protocols available. See also the link attached.
Best, -Peter
https://www.ncbi.nlm.nih.gov/pubmed/18546159
even 1:1 water/ACN + 0,1TFA is good enough and in some cases might be better.
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